As the terrified tornado-whipped students of Briarwood Elementary School in Moore, Okla., cowered on their hands and knees with backpacks over their heads, tearfully pleading for their parents, they asked their teacher, "Is this really happening?"

Sheri Bittle, a first-grade teacher at Briarwood, today recounted the horror of Monday's twister that she said sounded like a train that kept barreling by as it ravaged her school.

"You could just feel the pressure just building like you were in an airplane, just the pressurization of the cabin and your ears popping and the debris starts flying and the roof falling in," Bittle told ABC News. "And everything in your classroom falling in on you."

The tornado tore a 12-mile path of destruction that killed 24 people, including nine children, and destroyed Plaza Towers Elementary School and Briarwood Elementary School in Moore. For many families, Monday ended in tears of joy after families were reunited. Others were left to wait, hoping for good news while fearing the worst.

"I actually saw the tornado coming straight toward us," Briarwood first-grade teacher Cindy Lowe told ABC News. "I knew there was no turning back then. It was coming. It wasn't something that I was watching on TV. This was really going to happen."

Teachers followed procedure, Bittle said, moving students to interior walls and the innermost area of the school. The children got down on their hands and knees, putting their hands over their heads.

"They were covering their heads with their backpacks," Bittle said. "There was so much debris falling. A roof beam fell on me and another teacher."

Bittle, who escaped major injury, lay on top of her children as the building collapsed around them and said all the teachers would have done the same. A teacher in the next room had a table leg impale her own leg.

"I was praying," Bittle said. "I yelled it over and over for the Lord to just cover us and save us and to keep us safe. And He did. My entire class was safe and well and got delivered to their parents. The teachers at Plaza Tower didn't have that blessing."

Seven of the nine children killed in the tornado were students at Plaza Towers Elementary school, officials said.

"I can't imagine," Bittle said through tears, "not being able to give those kids back to their parents that brought them to me that morning."

Oklahoma County Commissioner Brian Maughan confirmed to ABC News affiliate KOCO-TV today that a number of children at Plaza Towers Elementary School remain unaccounted for.

"It's just a very graphic situation for even those of us who've come obviously well after the storm has passed," he said.

The storm tore off Plaza Towers' roof, knocked down walls and turned the playground into a mass of twisted plastic and metal. Rescue workers passed the survivors down a human chain to the triage center in the parking lot after the tornado passed directly over the school. Briarwood Elementary School received a "direct hit" from the twister and was also destroyed, with its roof and walls blown off.

"You just never imagine that you're going to walk out of your classroom and there's going to be nothing there," Bittle said.

Lowe said that she has not been so sleep yet because, "Every time I close my eyes, that's what I see. And it's very scary."

Both teachers rebuffed the term "hero" when asked about the praise they were receiving.

"It wasn't heroism, it was survival," Lowe said. "I just wanted to keep them all safe. It was my responsibility when they're in my classroom and that's where we were."

"Your child is my child. All day long and all year long, from August to May," Bittle said. "And I will do anything to take care of them."

"Safety is our main priority and the decisions we make are always with safety in mind," Susan Pierce, superintendent of Moore Schools, said at a news conference today. "We are in the process of learning as much as we can about what has happened and we are reviewing our emergency procedures today."

The two schools were not funded for safe rooms, according to state Director of Emergency Management Albert Ashwood.

"You have a limited amount of funds that are based on disasters you've had in the past that are used for mitigation measures and when you have limited number of funds, you set priorities for what schools you do want to ask for," Ashwood said at the news conference.

He said Briarwood and Plaza Towers were not being left out, but, rather, had not been brought forward yet for safe rooms.

"We're going to be looking to try and up that number and try and get more safe rooms in schools across the state, the entire state," Ashwood said.

One sixth-grade boy from Briarwood named Brady said he and other students took cover in a bathroom.

"I was in my classroom building and we were told to get in our tornado precaution system. Then they moved us to the boys and girls bathroom," he said.

"Cinderblocks and everything collapsed on them but they were underneath so that kind of saved them a little bit, but I mean they were trapped in there."

Josiah Parker, 8, escaped Briarwood unharmed but couldn't find his parents in the immediate aftermath of the tornado.

"If our school is crushed, my house is like directly behind the pond and so I think it might be crushed, too. If my mom and dad are still alive, they're probably going to take us to a hotel," Josiah said.

Students remained at Briarwood despite the tornado warnings because there were safe areas they could be protected.

Moore resident Andrew Wheeler credits a Briarwood teacher with keeping his son safe as the tornado wrecked havoc on the building.

"The teacher held their heads, and bricks and everything were falling all over the kids," he said. "She got her arm injured. One of the other boys on her other side got a big gash in his head, but he's OK."

Wheeler's son, Gabriel, says his teacher stood with the class the entire time and told them to act as they did in practice drills.

"The roof came off and then I felt something and it was just raining clay on me and all that," Gabriel said.

This twister was the latest in a group of violent storms that swept through the Midwest, starting Sunday, that has now left dozens of people dead.